A musical clock is a clock that marks the hours of the day with a musical tune played from a spiked cylinder either on bells, organ pipes, bellows, combs and even dulcimer strings. The earliest ones began in mainly churches and would be used to mark times for the public and for farmers in fields to tell them when it was sunset dawn and lunchtime.

The earliest known domestic one is by Nicholas Vallin, made in 1598, and it currently resides in the British Museum in London. This clock plays a different piece of music on every 1/4 hour. However some purists argue this clock is still technically a quarter chiming clock due to the quarter past melody only being around 8 notes long. The hour melody is certainly a tune though.

In terms of domestic clocks—most particular early ones—all the European clocks played tunes on carillons of bells from a large spiked drum within the clock. Many of these were in bracket clock form and there are a majority of longcase ones too. Some played their tunes each hour while others played every 3 or 4 hours usually either preceded or followed by the hour strikes.

Builders in the Black Forest later started to make trumpeteer musical clocks which played on horn bellows and have animated figures appear (usually of some kind of trumpeter), and appear to be blowing out the tune. Some of the London clock makers also started using organ mechanisms and coned cylinder-type music boxes; some were even combined with a set of bells to play tunes using both instruments implemented, although these are much rarer.

Musical clocks are even more interesting because they can play music using as few as 6 bells but usually with multiple hammers for quick note succession, but on average most would have 8, 10, 12 or 13 bells and multiple hammers, particularly if it has a lot more complex tunes. There are always exceptions and there are musical clocks out there with 16 to even 20 bells and usually have around 14–15 different tunes. On average most have 2–7 tunes selectable via a subsidiary dial.

In fact, some musical clocks were made with interchangeable spike drums allowing the owner to peg them to play whatever tune they desired, although these were very rare. Most all had their own specially made music spiked drums.

No matter what kind of musical clock it is: a turret/church clock, a bracket clock, a carriage clock, a longcase clock, an organ clock, or whatever else, the same basic system of how the clock plays its tunes is the same. It all revolves around a large cylinder which is spiked and pushed the relevant hammers or combs.

Beginning in the 1988, Rhythm Small World Clocks introduced modern battery powered musical clocks. Storing their music on computer chips, the first models played 6 melodies in rotation. Newer clocks play up to 18 melodies including Christmas tunes. Rhythm Small World Clocks was the only major brand in the market until 2000 when Seiko introduced their Melodies in Motion Clocks. Both Seiko and Rhythm musical clocks perform a new melody every hour on the hour and feature a light sensor which automatically switches off the music in the dark. Modern musical clocks play popular, country, classical or holiday melodies. The most popular modern musical clocks have elaborate motions where the clock face opens up revealing crystals, flashing lights, or other eye catching details.